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I have completed bits of my EM training from India. Currently I am boarded with credentials from Christian Medical College, Vellore and also from the prestigious Royal College of Emergency Medicine, UK.  I am currently working in London as an A&E doctor, trying to appreciate the differences in the practise and culture of Emergency Medicine across different healthcare systems. I have always been an avid FOAMed supporter because FOAMed played an indispensable role during the days of my initial training. Through this blog, I aspire to disseminate knowledge and stay up to date with the EM literature. 

Monday, April 3, 2017

Hypothermic patient in ED





Hypothermia is defined as a temperature of <35C. It is a common presentation in the Emergency Departments esp in elderly population with ? Sepsis. Geriatric population is prone to suffer from hypothermia due to poor mobility and altered temperature perception in addition to the environmental factors. Let's look at the common causes of hypothermia:
Causes

  • Environmental (often Accidental)
  • Hypoglycaemia (hypothalamic dysfunction secondary to glucopenia)
  • Hypothyroidism
  • Hypopituitarism
  • Hypoadrenalism
  • Hypothalamic Dysfunction (Tumor, Stroke, Infarction)
  • Sedatives and Alcohol
  • Sepsis
  • Massive Blood Transfusion
  • Burns and Exfoliative Dermatitis




Systemic Effects

CVS - BP and CO rise initially but later there is a phase of CVS depression and a general slow down of metabolism. This may lead to hypotension which is exacerbated by concomitant hypovolumia. Hypothermia usually causes bradyarrythmiats such as slow AF, sinus bradycardia, J waves, AV blocks, QTc prolongation on EKG. The management should focus on rewarming rather than administering anti-arrythmics. Also, hypothermic myocardium is irritable, and ventricular fibrillation may be induced by rough handling of the patient.

RS - Decrease O2 utility and less CO2 production. Patients may show a respiratory alkalosis or acidosis due to CNS depression. Lactate may be elevated due to shivering and hypoxia. There is also depression of gag and cough reflex making aspiration likely. Hypothermia causes a leftward shift of the oxyhemoglobin dissociation curve and thus impairs oxygen release to tissues. 

CNS - Confusion, lethargy, coma and unreactive pupils. There is decreased blood flow and cerebral protection against ischemic damages. Do not pronounce them dead until you are 100% sure. Use ECHO, ECG and Clinical judgment before you declare them dead.

Renal - Cold induced diuresis which contributes to volume loss, risk of rhabdo and AKI. 

Haematological - Hemoconcentration, thrombotic and embolic complications, DIC and Hypothermia induced coagulopathy. This coagulopathy may not be evident of blood tests but seen clinically. 


Investigations
  • Blood Glucose
  • Septic Screen (including CXR, Urine)
  • TSH
  • Creat Kinase
  • ECG
  • Heat CT (Consider after a period of observation - Every elderly with hypothermia does not need a Head CT)

Management
  • ABCs
  • Take up to 30 seconds to assess before commencing chest compressions - Use ECHO, feel for pulses and watch for respiratory movements. Handle them gently to avoid irritating the myocardium. If it is a hypothermic arrest then administer epinephrine every 6-10 minutes unless they are re-warmed and hypothermic arrhythmias may not respond to Cardioversion. Focus on warming in such a scenario
  • Warm O2 and Warm fluids
  • External Warming Blankets. Rapid rewarming is rarely needed. There are other rescue intensive and invasive methods such as pleura/peritoneal/GI/Bladder lasagne and ECMO. 
  • Arrhythmias - Rewarm then and only then think about anti-arrythmics
  • Antibiotics if concerned about Sepsis
  • Parenteral Thiamine for critically ill/malnourished/alcoholics/unexplained lactic acidosis
  • Steroids for septic shock refractory to one vasopressor/adrenal crisis and severe hypothyroidism

Unless there is obvious evidence, death in hypothermia must be defined as a failure to revive with rewarming (at least a core T of 30C)

Take Home:
Think beyond sepsis and environmental causes of hypothermia, think Endocrine causes!

Posted by:

              
     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic



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